1. Field of the Invention
The present invention is related to a composite material and, particularly to a thermally reversible composite material.
2. Description of the Prior Art
The Diels-Alder reaction, also called the “[4+2]cycloaddition reaction,” was proposed in 1928 by German chemists, Otto Diels and Kurt Alder, who found that by adding an electron-withdrawing group of an alkyne or alken to a conjugated diene, a cyclohexene can be formed. According to many researches, the Diels-Alder reaction is a thermally reversible reaction, and a diene and dienophile are mainly used to carry out the cycloaddition reaction. At high temperatures, the Diels-Alder reaction tends to occur in the reverse direction. It is so called the “Retro-Diels-Alder reaction.” When the Retro-Diels-Alder reaction happens, a catalytic agent is not necessary. Only high temperature is required for the Retro-Diels-Alder reaction to take place. For instance, furan and maleic anhydride can react with each other to combine the dienes thereof and form a cycloaddition polymer. However, such polymer will decompose into a diene and a dienophile at a temperature which is equal to or higher than its melting point.
Package materials usually are formed from thermosetting cross-link polymers. However, after the cross-link polymers are cured, the packaging can not be undone or patched in case of flaws. That results in high manufacturing costs. Since the requirements of environmental protection are getting higher and higher, the green (or environment-friendly) package is the trend for the market development. Therefore, it is important for the industries to develop a package material for package rework or repair.